• they are responsible for immune defense

1⁰=thymus, bone marrow

2⁰=MALT(mucosa assoc. lymphoid tissue), tonsils and lymph which filter lymph, and the spleen which filters antigen in blood

• lies just over heart
• small, encapsulated, 2 lobes
• begins to breakdown(atrophy) after 1st few years of life but does continue to function(tissue is replace by fat)
• capsule of dense CT, further divided into lobules(each has a cortex and a medulla), the cortex stains darker due to T-cells

D. George's syndrome: congenital failure of the thymus

• does not develop well
• no T-cell maturation, death early from multiple infections

• encapsulated organs along path of lymph vessels
• filter bacteria and viruses
•  find in neck and arm pit, groin, along major vessels of body
• small, soft, less than 3 cm

• have 3 regions: cortex, paracortex, medulla(all 3 are rich in sinusoids)

[image]

• endothelial lined spaces where lymph percolates
• outside of medulla there are "medullary cords"(fingerlike projections)

• has lymphoid nodules which are compartmentalized aggregates of B-cells

• largest
• in upper left quadrant of body cavity
• capsule of dense CT
• has mesothelium
• filters blood by destroying old and nonfunctional RBCs and exposes antigen to B/T cells
• contains "hilum"-where BV enter and leave
• in fresh tissue, white areas=white pulp and red areas=red pulp

• closley assoc. with "central arteriole"
• surrounded by a sheath called PALS(periarterial lymphoid sheath which contains T-cells)
• inside the sheath there are lighter staining B-cells b/c they are antigenically stimulated
• outside PALS is "marginal zone" which separates white pulp from red pulp

• has splenic sinuses and cords of Billroth
• resembles a sponge because spaces are sinuses and cords are the spongy material

• GALT(gut assoc. lymphoid tissue)
• diffuse areas of lymphoid tissue that lie just deep to lumen of digestive tract(ileum)
• MALT is an umbrella term for all mucosal assoc. lymphoid tissue

• incompletely encapsulated
• aggregations of lymphoid nodules
•  guard entrance to oral pharnyx(in path of airborne and antigens)

1. Palantine
2. tubal
3. Pharyngeal
4. lingual

[image]

1. Palatine

2. tubal

1. at boundary of oral cavity and oral pharynx(sides of

oropharynx)

2. roof; posterior to auditory tube

• on roof of nasal pharynx
• sometimes crypts are refered to as pleats
• called adenoids when inflamed

• skin, sweat glands, seabaceous glands, hair and nails
• largest organ in body=16% of body weight

• cover for soft tissues
• protection against injury, dessication, bacterial invasion
• regulation of body temp.
• reception of sensations
• excretion from sweat glands
• absorption of UV light for Vit. D synthesis

1. epidermis
2. dermis
3. hypodermis

• deep to epidermis, made of CT
• at junction of these 2 there are epidermal and dermal ridges

[image]

• superficial fascia, covers body just deep to skin
• different areas of the skin have varying thicknesses
• palms of hands and soles of feet=thick
• eyelids=thin

1. keratinocytes
2. melanocytes
3. langerhans cells
4. merkel cells

• make up largest pop'n of epidermal cells
• arranged in 5 layers
• mitotic activity at the base renews cells

-from bottom up-

1. stratum basale
2. stratum spinosum
3. stratum granulosum
4. stratum lucidum
5. stratum corneum

• 1-3 make up the malpighian layer

• deepest; supported by basal lamina
• single layer of mitotically active cuboidal cells

• thickest layer; flattened cells
• also have mitotically active keratinocytes

• 3-5 layers of keratinocytes
• most superficial layer that posses nuclei
• have granules that secrete a waxy substance that covers cells

• shiny, clear, lightly staining, thin layer
• only seen in thick skin
• appears refractable due to poor staining
• where organelles and cytoplasm are disrupted

• most superficial layer of skin
• numerous layers of keratinized epi
• epi cells are flattened and lack nucleus
• cells near surface=squames
• when squames sloughed=desquamated

• dendritic cells are named based on tissue of residence
• scattered in epidermis but primarily in stratum spinosum(largest area of epi)
• also found in dermis and found in oral cavity, esophagus, and vaginal tissue
• function in immune response-phagocytose and process antigens

• interspersed among keratinocytes of S. basale
• especially abundant in fingertips
• involved in sensory perception and are assoc. with nerves in a complex

• present in the S. basale
• produce melanin; brown pigment that contributes to skin color

• lies deep to epidermis
• 2 layers: top=papillary(loose) bottom=reticular(dense)
• made of CT
• thicker in men
• thicker on dorsal side of body

• interdigitates with epidermis
• contains fibroblasts and immune cells
• contains capillaries that nourish epidermis and control temp.
• contains some mechanoreceptors

• continuous with papillary layer
• made of CT and elastic fibers
• same cells as papillary layer but sparse; has some fat
• sweat glands, sebaceous glands, and hair follicles derived from epidermis in embryo but take up permanent residence in the dermis
• small smooth m. fibers present, called Arrector Pili m.

• assoc. with hair follicles and cause wrinkling with exposure to cold=goose bumps

1. Freckles
2. Psoriasis
3. Warts
4. Basal cell carcinoma
5. Squamous cell carcinoma

• hyperpigmented spots on sun exposed skin esp. i those people sensitive to sun
• usually seen by age 3
• result of increased melanin production
• tend to fade in winter

• patchy lesions from increased keratinocyte production(accelerated cell cycle)
• have accumulation of kerat. in stratum corneum
• common in scalp, knees, elbows, nails
• manageable

• benign growths of epidermis
• caused by infection of kerat. with pappiloma virus
• excess growth of kerat. with scaling

• most common human malignancy
• arises from s. basale
• caused by UV exposure
• do not metastisize but cause heavy damage in area

• second most common skin cancer
• kerat.
• may metastisize
• caused by several things: UV, x-ray, soot, chemical carcinogens, arsenic

1. a. eccrine & b. apocrine
2. sebaceous
3. mammory

• 3-4 million i skin(invaginations of epithelium)
• duct opens into ski to release sweat
• secretory protion has 2 cell types: clear and dark

1. clear-secrete watery substance
2. dark-secrete mucous rich substance

(both mix in a duct after being secreted)

• also sweat glands
• found in arm pit, areola of nipple, anal region, auditory canal, eyelids
• embedded deeper into the dermis

• found all over body exept palms and soles of feet
• most abundant in scalp, forehead, and face
• secrete sebum(a waxy mixture of of triglycerides and cholesterol
• maintain skin texture and hair flexibility
• find assoc. with hair follicles
• become active at puberty

• invagination of epidermis in to dermis
• expanded end=root and indents to form papilla
• papilla rich in capillaries to nourish and control growth
• "matrix"-bulk of cells that control division and is homologous to s. basale

[image]

• nail proper is heavily keratinized epi. cells(nail plate)
• develops from 'nail matrix' enderneath nail and becomes keratinized

[image]

• lines oral cavity and is strat. sq. non-kerat.
• regions that are expose to friction and shearing are partly keratinized
• contains 3 salivary glands that open into oral cavity

1. parotid
2. submandibular
3. submaxillary

• core has skeleltal muscle for mobility
• 3 zones

1. external aspect
2. vermillion/red zone
3. internal/mucous aspect

[image]

• thin skin, hair, seb. glands, sweat glands

• red area covered by skin

• wet, strat. squamous non-kerat.,
• underneath is CT and mucous and salivary glands

Teeth

-2 sets in humans-

1. 20 deciduous(milk) replaced by»»
2. 32 permanent(adult)

[image]

• alveolus-bony socket that suspends tooth
• periodental ligament-dense CT-also suspends tooth
• gingiva(gums) support tooth-seals cavity where tooth resides
• crown-visible portion
• root-housed in alveolus

1. enamel
2. dentin
3. cementum

• hardest substance in body
• translucent, color due to underlying dentin
• produced by ameoblasts
• enamel rods that are the result of adherance of rod segments to each other
• enamel is non-vital; ameloblasts die before tooth is erupted;body cannot repair enamel

• second hardest
• yellowish; does have some elasticity to protect enamel
• has underlying calcification called Lines of Owen
• is capable of self repair

• restricted to root
• contains cells=cementocytes in lacunae
• has caniliculi that extend to vascularized periodental ligament for nourishment

• extensive vasular and nerve supply, has some lymph elements
• communicates with periodontal ligament
• vessels and nerves travel to periodontal ligament via opening called apocal foramen

1. odontoblastic zone-single layer of odontoblasts
2. cell-free zone-has no cells
3. cell-rich zone-rich in fibroblasts, mesenchymal cells

• loose CT, lacks adipose, highly vascularized, has 'pulp stones'(calcified elements)

• tough, mucous membrane
• strat. sq., partly kerat. or non-kerat.
• deep part=dense CT
• region that connects to enamel=junctional epi.

• oral/nasal cavities are separated by soft/hard plate

1. soft-more posterior, core has skel. m.
2. hard-anterior in the mouth; bony shelf

• largest structure oral cavity
• skel. m.=outside-extrinsic, inside-intrinsic
• posterior 3rd is uneven due to tonsils

Parts of the tongue:

papillae

1. filiform
2. fungiform
3. folliate
4. circumvallate

• slender, velvety appearance
• strat. sq. kerat.
• scraping food
• no taste bud

• posteriorlateral
• vertical furrows
• present in neonate but degenerate by 2 or 3
• salivary glands of Von Ebner empty into furrows

• have 8-12
• submerged into surface surrounded by groove
• taste buds present

• have broad 'cap'
• blood courses through capillaries at top=red dot
• do have taste buds

Parts of the tongue:

Taste buds

• intraepithelial sensory organs
• about 3,000 on surface of tongue and back of oral cavity
• each bud has 60-80 spindle shaped cells
• narrow end at surface has 'taste pore'(where hairs protrude for perception)
• life span of cells is about 10 days

1. sweet
2. sour
3. bitter
4. salty
5. chinese=umami-pungent

• taste perception comes from receptors/ion channels